DESANDROUINS, JEAN-NICOLAS, army officer and military engineer; b. 7 Jan. 1729 at Verdun, France, eldest child of Benoît-Nicolas Desandrouins and Marie-Scholastique Hallot; d. unmarried 11 Dec. 1792 in Paris, France.

After a classical education at the local Jesuit college, Jean-Nicolas Desandrouins was commissioned lieutenant in the Régiment de Beauce in 1746. Five years later, following active combat service in the War of the Austrian Succession, he entered the military engineering school at Mézières (Charleville-Mézières). He graduated with distinction, and was admitted to the engineer corps in 1752.

Following three years’ service at Dunkerque, Desandrouins was promoted second captain and sent to Canada as assistant to Jean-Claude-Henri de Lombard* de Combles. Arriving at Quebec on 18 May 1756 and at Fort Frontenac (Kingston, Ont.) a month later, he drew up plans for improving the latter’s defences and on 8 July reconnoitred Oswego (Chouaguen) with François-Marc-Antoine Le Mercier in preparation for Montcalm*’s attack. After Lombard’s death on 11 August, Desandrouins, the sole remaining regular engineer, played a key role in the siege and capture of Oswego. He constructed an approach road for Le Mercier’s artillery through wooded and partly swampy country in one day, and his advice on the siting of trenches was accepted by Colonel François-Charles de Bourlamaque* after the trenches dug by Captain Pierre Pouchot* were found to be vulnerable to British artillery fire.

Desandrouins’s contribution to Montcalm’s victories of 1757 and 1758 was similarly important. In 1757 he carried out a reconnaissance of Fort William Henry (also called Fort George; now Lake George, N.Y.), and during the siege directed the digging of approach trenches by 300 men who worked night and day in relays under fire. After wintering at Quebec, Desandrouins went to Fort Carillon (Ticonderoga, N.Y.) to help Nicolas Sarrebource* Maladre de Pontleroy reconnoitre, prepare defensive positions, and advise infantry commanders on field fortifications. The speed at which Desandrouins worked under fire during Abercromby’s attack of 8 July 1758 earned him the cross of Saint-Louis.

During the winter of 1758–59 Desandrouins prepared appreciations of Carillon and of Canada in general. In 1759, as Bourlamaque’s senior engineer, he constructed new defensive positions in the Richelieu River-Lake Champlain sector against Jeffery Amherst’s cautiously advancing force. From mid August until March 1760 he was responsible for the construction and command of Fort Lévis (east of Prescott, Ont.). As engineer and aide-de-camp to Lévis, he supervised the digging of trenches during the siege of Quebec, and when Lévis’s army was retreating upstream to Montreal, he assisted in delaying actions at Sorel.

Later that year, after the surrender of the colony, Desandrouins returned to France and continued a distinguished career in the engineer corps for another 31 years. Between 1761 and 1780 he served first in Malta and then in various places in France, at Strasbourg, Neuf-Brisach, Thionville, Saint-Omer, Bapaume, Nancy, and Sarrelouis (now in the Federal Republic of Germany), constructing all kinds of works including a canal, a hospital, and a bridge. Promoted lieutenant-colonel in 1774 and colonel in 1779, he became in 1780 commander of engineers in the Comte de Rochambeau’s expeditionary force to America. Although illness prevented him from taking part in the siege of Yorktown, Virginia, his services won him not only a special French pension but also membership in the Society of the Cincinnati, an American military and patriotic organization. After a devastating shipwreck off Curaçao in February 1783 which resulted in the loss of many of his possessions, including a large part of his private papers, Desandrouins returned to France. Appointed director of fortifications at Brest in 1785, he was promoted major-general in 1788. Three years later, however, along with other senior officers of the engineer corps, he was forced to retire by the revolutionary government. His income sharply reduced by a new pensions policy, Desandrouins was considered for appointment to a committee on the fortifications of Paris but died before he could be assigned to the post.

Desandrouins’s extant writings, maps, and plans are useful source material for the Seven Years’ War in North America. Though his comments on Canada reflect the prevalent bias of the French regular army against Canadians and Indians, within those limits he reveals himself as an astute observer of the events and conditions of his time. Like other engineer officers, who tended to have a superior education, he played an important staff role as adviser to commanders in matters not directly related to his technical duties.

F. J. Thorpe